This section provides background information related to the present disclosure which is not necessarily prior art.
A typical automotive engine is an internal combustion device which includes an engine block having multiple cylinders. Each cylinder supports a piston for reciprocating movement. A cylinder head is coupled to a top surface of the engine block such that the block and head define a combustion chamber. The cylinder head includes a set of intake ports and a set of exhaust ports for each cylinder which, in combination with the intake valves and exhaust valves, allow combustion gases to enter and exit the combustion chambers. An intake manifold and an exhaust manifold are typically coupled to the cylinder head for routing the combustion gases to and from the intake and exhaust ports.
Such an automotive engine may be equipped with secondary air injection (SAIR) as part of the emissions control system. The SAIR system injects air into the exhaust stream to allow for a more complete combustion of exhaust gases by supporting the efficient function of the catalytic converter. When the engine is cold, the injected air can clean up the relatively rich exhaust and bring the catalytic converter to operating temperature quickly. Once the engine is warm, the injected air can assist with catalysis of unburned hydrocarbons and carbon monoxide. SAIR systems may be implemented in a variety of ways with either pumped air injection or aspirated air injection. Regardless of the method of implementation, the system must provide an air path for injecting air into the exhaust gas stream near the combustion chamber of the engine, either at the exhaust ports in the cylinder head or in the exhaust manifold.
The implementation of SAIR systems requires additional components such as pumps, valves and fluid passageways. With the recent developments in cylinder block and cylinder head design and fabrication, it is desirable to integrate these components for space efficiencies. Likewise, it is desirable to optimize the control of air injection for improved SAIR performance.